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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2012 The Guava Authors<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * Licensed under the Apache License, Version 2.0 (the "License");<a name="line.4"></a>
<span class="sourceLineNo">005</span> * you may not use this file except in compliance with the License.<a name="line.5"></a>
<span class="sourceLineNo">006</span> * You may obtain a copy of the License at<a name="line.6"></a>
<span class="sourceLineNo">007</span> *<a name="line.7"></a>
<span class="sourceLineNo">008</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * Unless required by applicable law or agreed to in writing, software<a name="line.10"></a>
<span class="sourceLineNo">011</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.11"></a>
<span class="sourceLineNo">012</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * See the License for the specific language governing permissions and<a name="line.13"></a>
<span class="sourceLineNo">014</span> * limitations under the License.<a name="line.14"></a>
<span class="sourceLineNo">015</span> */<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>package com.google.common.reflect;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import com.google.common.annotations.Beta;<a name="line.19"></a>
<span class="sourceLineNo">020</span><a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.lang.reflect.InvocationHandler;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.lang.reflect.Method;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import java.lang.reflect.Proxy;<a name="line.23"></a>
<span class="sourceLineNo">024</span><a name="line.24"></a>
<span class="sourceLineNo">025</span>import javax.annotation.Nullable;<a name="line.25"></a>
<span class="sourceLineNo">026</span><a name="line.26"></a>
<span class="sourceLineNo">027</span>/**<a name="line.27"></a>
<span class="sourceLineNo">028</span> * Abstract implementation of {@link InvocationHandler} that handles {@link Object#equals},<a name="line.28"></a>
<span class="sourceLineNo">029</span> * {@link Object#hashCode} and {@link Object#toString}.<a name="line.29"></a>
<span class="sourceLineNo">030</span> *<a name="line.30"></a>
<span class="sourceLineNo">031</span> * @author Ben Yu<a name="line.31"></a>
<span class="sourceLineNo">032</span> * @since 12.0<a name="line.32"></a>
<span class="sourceLineNo">033</span> */<a name="line.33"></a>
<span class="sourceLineNo">034</span>@Beta<a name="line.34"></a>
<span class="sourceLineNo">035</span>public abstract class AbstractInvocationHandler implements InvocationHandler {<a name="line.35"></a>
<span class="sourceLineNo">036</span><a name="line.36"></a>
<span class="sourceLineNo">037</span>  private static final Object[] NO_ARGS = {};<a name="line.37"></a>
<span class="sourceLineNo">038</span><a name="line.38"></a>
<span class="sourceLineNo">039</span>  /**<a name="line.39"></a>
<span class="sourceLineNo">040</span>   * {@inheritDoc}<a name="line.40"></a>
<span class="sourceLineNo">041</span>   *<a name="line.41"></a>
<span class="sourceLineNo">042</span>   * &lt;p&gt;&lt;ul&gt;<a name="line.42"></a>
<span class="sourceLineNo">043</span>   * &lt;li&gt;{@code proxy.hashCode()} delegates to {@link AbstractInvocationHandler#hashCode}<a name="line.43"></a>
<span class="sourceLineNo">044</span>   * &lt;li&gt;{@code proxy.toString()} delegates to {@link AbstractInvocationHandler#toString}<a name="line.44"></a>
<span class="sourceLineNo">045</span>   * &lt;li&gt;{@code proxy.equals(argument)} returns true if: &lt;ul&gt;<a name="line.45"></a>
<span class="sourceLineNo">046</span>   *   &lt;li&gt;{@code proxy} and {@code argument} are of the same type<a name="line.46"></a>
<span class="sourceLineNo">047</span>   *   &lt;li&gt;and {@link AbstractInvocationHandler#equals} returns true for the {@link<a name="line.47"></a>
<span class="sourceLineNo">048</span>   *       InvocationHandler} of {@code argument}<a name="line.48"></a>
<span class="sourceLineNo">049</span>   *   &lt;/ul&gt;<a name="line.49"></a>
<span class="sourceLineNo">050</span>   * &lt;li&gt;other method calls are dispatched to {@link #handleInvocation}.<a name="line.50"></a>
<span class="sourceLineNo">051</span>   * &lt;/ul&gt;<a name="line.51"></a>
<span class="sourceLineNo">052</span>   */<a name="line.52"></a>
<span class="sourceLineNo">053</span>  @Override public final Object invoke(Object proxy, Method method, @Nullable Object[] args)<a name="line.53"></a>
<span class="sourceLineNo">054</span>      throws Throwable {<a name="line.54"></a>
<span class="sourceLineNo">055</span>    if (args == null) {<a name="line.55"></a>
<span class="sourceLineNo">056</span>      args = NO_ARGS;<a name="line.56"></a>
<span class="sourceLineNo">057</span>    }<a name="line.57"></a>
<span class="sourceLineNo">058</span>    if (args.length == 0 &amp;&amp; method.getName().equals("hashCode")) {<a name="line.58"></a>
<span class="sourceLineNo">059</span>      return hashCode();<a name="line.59"></a>
<span class="sourceLineNo">060</span>    }<a name="line.60"></a>
<span class="sourceLineNo">061</span>    if (args.length == 1<a name="line.61"></a>
<span class="sourceLineNo">062</span>        &amp;&amp; method.getName().equals("equals")<a name="line.62"></a>
<span class="sourceLineNo">063</span>        &amp;&amp; method.getParameterTypes()[0] == Object.class) {<a name="line.63"></a>
<span class="sourceLineNo">064</span>      Object arg = args[0];<a name="line.64"></a>
<span class="sourceLineNo">065</span>      return proxy.getClass().isInstance(arg) &amp;&amp; equals(Proxy.getInvocationHandler(arg));<a name="line.65"></a>
<span class="sourceLineNo">066</span>    }<a name="line.66"></a>
<span class="sourceLineNo">067</span>    if (args.length == 0 &amp;&amp; method.getName().equals("toString")) {<a name="line.67"></a>
<span class="sourceLineNo">068</span>      return toString();<a name="line.68"></a>
<span class="sourceLineNo">069</span>    }<a name="line.69"></a>
<span class="sourceLineNo">070</span>    return handleInvocation(proxy, method, args);<a name="line.70"></a>
<span class="sourceLineNo">071</span>  }<a name="line.71"></a>
<span class="sourceLineNo">072</span><a name="line.72"></a>
<span class="sourceLineNo">073</span>  /**<a name="line.73"></a>
<span class="sourceLineNo">074</span>   * {@link #invoke} delegates to this method upon any method invocation on the proxy instance,<a name="line.74"></a>
<span class="sourceLineNo">075</span>   * except {@link Object#equals}, {@link Object#hashCode} and {@link Object#toString}. The result<a name="line.75"></a>
<span class="sourceLineNo">076</span>   * will be returned as the proxied method's return value.<a name="line.76"></a>
<span class="sourceLineNo">077</span>   * <a name="line.77"></a>
<span class="sourceLineNo">078</span>   * &lt;p&gt;Unlike {@link #invoke}, {@code args} will never be null. When the method has no parameter,<a name="line.78"></a>
<span class="sourceLineNo">079</span>   * an empty array is passed in.<a name="line.79"></a>
<span class="sourceLineNo">080</span>   */<a name="line.80"></a>
<span class="sourceLineNo">081</span>  protected abstract Object handleInvocation(Object proxy, Method method, Object[] args)<a name="line.81"></a>
<span class="sourceLineNo">082</span>      throws Throwable;<a name="line.82"></a>
<span class="sourceLineNo">083</span><a name="line.83"></a>
<span class="sourceLineNo">084</span>  /**<a name="line.84"></a>
<span class="sourceLineNo">085</span>   * By default delegates to {@link Object#equals} so instances are only equal if they are<a name="line.85"></a>
<span class="sourceLineNo">086</span>   * identical. {@code proxy.equals(argument)} returns true if: &lt;ul&gt;<a name="line.86"></a>
<span class="sourceLineNo">087</span>   * &lt;li&gt;{@code proxy} and {@code argument} are of the same type<a name="line.87"></a>
<span class="sourceLineNo">088</span>   * &lt;li&gt;and this method returns true for the {@link InvocationHandler} of {@code argument}<a name="line.88"></a>
<span class="sourceLineNo">089</span>   * &lt;/ul&gt;<a name="line.89"></a>
<span class="sourceLineNo">090</span>   * Subclasses can override this method to provide custom equality.<a name="line.90"></a>
<span class="sourceLineNo">091</span>   */<a name="line.91"></a>
<span class="sourceLineNo">092</span>  @Override public boolean equals(Object obj) {<a name="line.92"></a>
<span class="sourceLineNo">093</span>    return super.equals(obj);<a name="line.93"></a>
<span class="sourceLineNo">094</span>  }<a name="line.94"></a>
<span class="sourceLineNo">095</span><a name="line.95"></a>
<span class="sourceLineNo">096</span>  /**<a name="line.96"></a>
<span class="sourceLineNo">097</span>   * By default delegates to {@link Object#hashCode}. The dynamic proxies' {@code hashCode()} will<a name="line.97"></a>
<span class="sourceLineNo">098</span>   * delegate to this method. Subclasses can override this method to provide custom equality.<a name="line.98"></a>
<span class="sourceLineNo">099</span>   */<a name="line.99"></a>
<span class="sourceLineNo">100</span>  @Override public int hashCode() {<a name="line.100"></a>
<span class="sourceLineNo">101</span>    return super.hashCode();<a name="line.101"></a>
<span class="sourceLineNo">102</span>  }<a name="line.102"></a>
<span class="sourceLineNo">103</span><a name="line.103"></a>
<span class="sourceLineNo">104</span>  /**<a name="line.104"></a>
<span class="sourceLineNo">105</span>   * By default delegates to {@link Object#toString}. The dynamic proxies' {@code toString()} will<a name="line.105"></a>
<span class="sourceLineNo">106</span>   * delegate to this method. Subclasses can override this method to provide custom string<a name="line.106"></a>
<span class="sourceLineNo">107</span>   * representation for the proxies.<a name="line.107"></a>
<span class="sourceLineNo">108</span>   */<a name="line.108"></a>
<span class="sourceLineNo">109</span>  @Override public String toString() {<a name="line.109"></a>
<span class="sourceLineNo">110</span>    return super.toString();<a name="line.110"></a>
<span class="sourceLineNo">111</span>  }<a name="line.111"></a>
<span class="sourceLineNo">112</span>}<a name="line.112"></a>




























































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